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    <title>
      Working with JREs
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    <h1>
      Working With JREs
    </h1>
    <p>
      You can <a href="../tasks/task-add_new_jre.htm">install</a> as many
      different Java Runtime Environments (JREs) as you like. JREs are used to
      run and debug java programs. Your JREs are managed on the <a href=
      "../reference/preferences/java/debug/ref-installed_jres.htm">Installed
      JREs</a> preference page.
    </p>

    <p>
      A JRE definition consists of:
    </p>
    <ul>
      <li>The type of the JRE (e.g. Standard VM or Standard 1.x.x VM)
      </li>
      <li>A name
      </li>
      <li>The location where the JRE is installed
      </li>
      <li>The system libraries containing the Java system classes (like
      java.lang.Object). Optionally, the system libraries can be associated
      with:
      <ul>
      <li>the <a href="../reference/ref-properties-source-attachment.htm">source file</a>
      containing the source for the classes in the JRE's CLASS files</li>
      <li>a javadoc location (URL)</li>
      <li><a href="../tasks/task-using_external_null_annotations.htm">external annotations</a>.</li>
      </ul>
      </li>

      <li>Other information needed by the VM to build, run and debug
      applications.
      </li>
    </ul>
    <p>
      You can <a href="../tasks/task-assign_default_jre.htm">switch</a> the
      default JRE for the workbench. The default JRE is used by default when
      building, running, and debugging applications. Alternatively, projects
      may <a href="../tasks/task-choose_config_jre.htm">specify</a> a specific
      JRE that they should be built and run with.
    </p>

    <h3 class="related">Related Concepts</h3>
      <a href="../concepts/concept-jdt.htm">Java development tools (JDT)</a>

    <h3 class="related">Related Tasks</h3>
      <a href="../tasks/task-add_new_jre.htm">Adding a new JRE
      definition</a><br />
      <a href="tasks-deleteJRE.htm">Deleting a JRE definition</a><br />
      <a href="../tasks/task-assign_default_jre.htm">Choosing a default
      JRE</a><br />
      <a href="../tasks/task-choose_config_jre.htm">Choosing a JRE for
      launching a project</a>

    <h3 class="related">Related References</h3>
      <a href=
      "../reference/preferences/java/debug/ref-installed_jres.htm">Installed
      JREs preference page</a>
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